Evolutionary transformations of centipede ultimate legs

In comparison to locomotory legs, the last pair of legs in Chilopoda – the ultimate legs – is particularly unique as no other legs in centipedes show a comparable functional, morphological, and behavioral diversity. These evolutionary transformed appendages are never or only rarely used for locomotion and can exhibit different morphologies associated with different functions. Sexual dimorphic characteristics suggest that ultimate legs play a pivotal role in intraspecific communication, mate finding and courtship behavior. Thus, centipede ultimate legs provide an excellent opportunity to explore diverse pathways of leg transformations. Ultimate legs in Scutigeromorpha (house centipedes) are extremely elongated and resemble antennae. The diversity, abundance and distribution of sensory structures, their association with elaborated primary processing centers in the nervous system, as well as electrophysiological experiments strongly suggest that these multi-annulated legs function as sensory appendages at the posterior end of the body. In Geophilomorpha (soil centipedes), ultimate legs may be sexually dimorphic and frequently covered with thousands of cuticular structures. However, these hairs do not resemble sensilla, but shafts of glandular structures. Thus, geophilomorph ultimate legs evolved a secretory function of yet unknown relevance. We show that centipede ultimate leg transformations are by no means restricted to external morphology, but that this particular centipede character was subjected to a cascade of adaptations.

Recommended citation: Sombke, A. & C. H. G. Müller (2020): Evolutionary transformations of centipede ultimate legs. Integrative and Comparative Biology, Volume 60, Supplement 1, Page e218. https://doi.org/10.1093/icb/icaa006